The present invention relates to pressure measurement techniques and specifically to pressure sensing devices such as pressure leak detectors. The present invention solves the problem of detecting pressure changes in a pressurized vessel without introducing additional leakage paths. There is a need for a highly reliable, relatively low cost pressure measurement technique that does not introduce additional leakage paths into a system. Pressure sensors often require some external energy source in order to monitor the sensor output. The present invention does not require an external or additional energy source in that the integral pressure sensor traps the medium when the vessel is pressurized and utilizes the trapped energy to activate the sensor.
The present invention also addresses the problem of verification of pneumatic system source pressure in containers used for various weapon systems. This present invention can also be applied to long and short term storage of hazardous waste, gaseous compounds, or chemicals where an inexpensive and reliable method for indicating the internal pressure change of a containment vessel is required. This new method of indicating the pressure status has numerous applications including use in automotive systems, actuation systems, fire extinguishers, pressure bladders, inflatable devices and many other areas involving pressurized vessels or storage tanks.
The related art can be separated into two general categories. The first category is pressure measurement techniques which broach the integrity of the pressurized vessel or system. The second category include those pressure measuring techniques which do not broach or otherwise introduce additional leakage paths to the pressurized vessel or system. The first category involves the most common methods of measuring the pressure of a sealed container. The use of pressure gauges and pressure transducers typically involves creating additional apertures or holes in the container. Alternatively, pressure gauges are often attached to existing orifices. In either situation these pressure sensing devices introduce at least one additional point from where the vessel or container can leak. The introduction of additional leakage points is a problem which the present invention solves.
Related techniques in the second category or for non-intrusive pressure indication techniques can involve the removal, isolation and subsequent weighing of the pressurized vessel. Frequently, this approach is not feasible given the size of the vessel, accessibility and other logistical constraints. Alternative techniques include measurement of vessel strain which often require sophisticated electronics to account for variables such as temperature. All of the related pressure measurement devices or techniques are not acceptable due to timeliness concerns, high complexity, low reliability, high cost, and other logistical considerations.